Field of the Invention
This invention relates generally to application specific projection systems and more particularly to three-dimensional object scanning systems. Even more particularly, the invention relates to structured light scanning systems.
Description of the Background Art
Structured light scanning systems are currently being used to measure the three-dimensional topography of objects. Such systems typically include a computer connected to both a projector (e.g., a liquid crystal on silicon (LCOS) projector) and a camera. During operation, the projector projects a plurality of narrow light bands on a three-dimensional surface or object. From the perspective of the projector, the narrow light bands appear as evenly distributed vertical and/or horizontal stripes. From the perspective of the camera, however, the narrow light bands appear as distorted stripes. The camera captures images of these distorted stripes and sends the image data to the computer for further processing. The computer then uses a series of algorithms that analyze the distortions to generate data indicative of the topography of the three-dimensional surface. Generally, such data is in the form of a two-dimensional array of three-dimensional vector values.
An LCOS projector typically includes an LCOS driver circuit, an LCOS panel (including an array of display pixels), a light source, and optics. The LCOS driver circuit receives video data from the computer and outputs pixel data indicative of narrow stripes. The LCOS panel receives the pixel data and loads it into the pixel array located thereon. The light source projects light that passes through a liquid crystal layer, reflects off of the individual pixels of the array, and passes back through the liquid crystal layer. One or more polarizers modulate the light reflected by individual pixels depending on the amount of polarization rotation induced by the liquid crystal layer, which in turn depends on the voltages asserted on the pixel electrodes. The illuminated micro-display is then focused onto an object/surface via the optics. As a result, the object/surface is illuminated with a series of stripes.
Although current structured light scanning systems provide an effective means to acquire three-dimensional topography data, they also have shortcomings. For example, current systems require a LCOS driver circuit to provide the LCOS panel with pixel data indicative of the narrow light bands. Of course, LCOS drivers are relatively complicated and expensive circuits.
What is needed, therefore, is a LCOS structured light scanning system that is simpler and more cost effective to manufacture than current systems.